1. Repeatedly putting a fitted sheet on a bed can cause “sheet-fitting palsy.”

The ailment, described in a recent case study, occurs when repetitive motion like trying to stretch a fitted sheet over a mattress creates a blood clot in an artery in the wrist. The result can be numbness, tingling, and weakness. One otherwise healthy 73-year-old sufferer saw her thumb become completely useless after one too many run-ins with a fitted sheet. Luckily surgery and physical therapy brought her back to normal — nonetheless, her story offers clear proof that fitted sheets are the worst.

2. Doing chores after you get home can boost stress hormones.

A 2011 study showed that doing chores after you get home from work can keep levels of the stress hormone cortisol from falling back to normal, as they otherwise might after a stressful day. For women, cortisol began to drop if their male partners pitched in to help. But for men, levels only fell if their partners did the work while they relaxed (which may be why the guy above looks so tense).

3. Carrying heavy loads of laundry causes shoulder problems.

Orthopedic Surgeon Denny Lie writes that damage to shoulder tendons, and the resultant “deep shoulder pain,” can be caused by a variety of daily activities: “A particularly disturbing trend is the number of patients who remember experiencing this pain after carrying clothes to dry on poles outside their flats.” This cat should be safe.

5. Too much housework makes people depressed.

In a recent study conducted in Brazil, women who suffered from “housework overload” were more likely than others to have mental disorders like depression or anxiety. Those who had to do excessive amounts of washing, ironing, cleaning, or cooking were about 9% more likely to have mental health problems than those whose housework load was more manageable.

6. Doing more chores than your partner can stress you out.

Earlier this year, a study of straight Swedish couples found that women tended to do more housework than men, and that this led to higher levels of anxiety, restlessness, and other psychological problems. However, women who reported being in a “gender-equal” relationship were less stressed if they had to do extra chores.